Dew Point Calculator
Calculate dew point from temperature and humidity — check comfort level
Air Temperature
°C
Relative Humidity (%)
%
Comfort by Dew Point
< 10°C — Dry, very comfortable
10–16°C — Comfortable
16–21°C — Slightly humid
21–24°C — Uncomfortable
> 24°C — Oppressive
Dew Point
Dew Point (°C)
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Dew Point (°F)
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Comfort Level
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Temp–Dew Spread
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Relative Humidity
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What is Dew Point?
The dew point is the temperature at which air must be cooled (at constant pressure and humidity) for water vapour to condense into liquid water (dew). When the air temperature equals the dew point, relative humidity is 100% and fog or dew forms.
Unlike relative humidity, dew point is an absolute measure of moisture in the air — it doesn't change when air temperature changes. A dew point above 21°C (70°F) is uncomfortable for most people; above 24°C (75°F) is oppressive. This is common in tropical areas and during Indian monsoon season.
lightbulb Example
30°C, 65% humidity (Mumbai summer):
1Using Magnus formula
2Dew point ≈ 22.8°C
✓ Very humid — quite uncomfortable
quizFrequently Asked Questions
What is the dew point and why does it matter?
The dew point is the temperature at which air becomes saturated and water vapour condenses into dew. When the dew point is close to the actual air temperature, humidity is near 100% and the air feels muggy. A dew point above 21°C (70°F) is considered oppressive; below 10°C (50°F) feels comfortable and dry.
What's the difference between dew point and relative humidity?
Relative humidity (RH) is a percentage that changes with temperature — the same amount of moisture at 20°C might be 80% RH, but at 30°C it's only 50% RH. Dew point is an absolute measure of moisture content in the air and doesn't change with temperature. Meteorologists prefer dew point because it's a more reliable comfort indicator.
What dew point causes indoor condensation problems?
Condensation forms on surfaces (windows, pipes, walls) when the surface temperature drops below the dew point. Setting your AC to 22°C in a room with a 23°C dew point will cause condensation on the AC unit and walls. Proper ventilation, insulation, and dehumidification are the solutions.